


Mind your manners

by Wolf_n_Bones



Category: Undertale (Video Game)
Genre: Attempted Murder, Cunnilingus, Dubious Consent, Ecto-Vagina (Undertale), Master/Pet, Other
Language: English
Status: Completed
Published: 2018-12-11
Updated: 2018-12-11
Packaged: 2019-09-16 12:53:06
Rating: Mature
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 2,604
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/16954401
Author URL: https://archiveofourown.org/users/Wolf_n_Bones/pseuds/Wolf_n_Bones
Summary: Blue finds out his brother is secretly doing naughty stuff with one of the humans... And he's not happy.





	Mind your manners

The echo flowers around Blueberry whispered. “Suspicious…. Home… fucking tease~…” Blue blocked out the rest as anger welled up in his soul, his sockets dark and hollow. He turned on his heel and made his way home. He didn’t know how long it had been going on but he could guess it had been a while. His pace was brisk, a default cheery façade on his skull until he entered the house. His grin fell to a scowl.

A few months back two humans had fallen to the Underground. A blonde with long hair and a (y/c) with a pixie cut. His brother had taken them home with him. Sans really needed to address his habit of taking in ‘strays’ it appeared… He had welcomed them like the others had and observed their behavior.

(Y/n) wasn’t one for physical contact other than battles, which they seem to enjoy a lot. Especially with Underfell Papyrus, since both keep antagonizing the other. They rather kept everyone at an arms-length the first days and until now they had only let Classic Papyrus and Underfell Sans (for some reason) close to them.

The blonde seemed to shy away from everyone until she was settled. She was a rather loud person and a _brat_. Blue didn’t like her much, especially now he knew what she had been doing with _his brother_ …

Blueberry hummed as he started on his tacos. He had to plan carefully or Papy would notice… He had planned on killing the humans and taking their souls… After all, it was necessary for joining the Royal Guard! Alphys would be so proud of him! He had just wished he had gotten the humans to trust him a bit more… It would make this easier~

The front door opened and closed, but Blue didn’t pay mind to it. Stirring the taco filling and tasting. “Smells good~” He heard a voice comment near his skull. He nearly jumped six feet into the air, dropping the ladle he was holding. He turned to see you standing there, looking mildly amused. The smell of alcohol and cigar smoke tickled his nasal cavity. You just got home from work…

You peer into the boiling pot, the content was gently simmering. The little blue skeleton was improving~ Your eyes glided back to Blue, who was fumbling with his words. It seemed you had rattled his bones. “Want me to set the table?” You ask him. He blushed and nodded.

“Yes, please.” He replied, a small smile pulling back on his skull as the shock faded. You smiled back and moved to get the plates and table cloth, leaving Blue to tend to the food. It didn’t take long as it was just the four of you tonight. Everyone else ate later or weren’t home until tomorrow.

“Blue I’m taking a shower, ok?” You shout as you make your way upstairs, eager to get rid of the stench of work. You heard a cheerful okay before you disappeared into the bathroom. You appeared fresh for dinner. Blue’s brother, Stretch, and your friend already sitting at the table though on opposite sides… Odd… You thought, looking at them closely. Something was up. Stretch hardly ever broke a sweat or was tense but here he was, sweating bullets and sitting stiffly on the chair. Your friend was squirmish too so you sat next to her and gave her a look to spill the beans.

“He knows…” She whispered. “And he’s not happy…” She was nervous. “Could you cover for us if shit hits the fan?” She pleaded. You gave her an incredulous look before sighing.

“Fine. But you owe me BIG time…” You responded in a growl. You hated bringing your work home. Blue appeared out of the kitchen with a tray of tacos.

“Let’s eat~!” He chirped, offering everyone a taco. You smiled taking one.

“Thanks for the food.” You reacted as the others took a taco as well. You wanted to take a bite but a gleam in the food caught your eye. To your horror and anger you pulled out a long, thin needle. He _did not_ just ruin perfectly good food… You dropped it on your plate and everyone halted their actions. Your friend instantly dropped their taco on the plate and spilled the content. Blue gasped as she did, clasping his hands to his cheekbones.

“Oh no! You spilled taco sauce on your clothes! I’ll go get something to clean it up with!” He ran to the kitchen and Stretch tensed, getting ready to spring into action. The spilled content was littered with long thin needles, a waste of perfectly good food. Your friend looked at them pissed but before she could get up to go confront the little blue skeleton he came out of the kitchen holding a sharp knife.

“Eh… Blue? What are you doing with (y/n)’s knife?” She asked nervously. The skeleton in question smiled gleefully.

“Oh nothing suspicious~” He chirped, Stretch paling at the words. “But I don’t think you’ll be able to ‘fucking’ tease your way out of this one!” He growled, blue magic flaring from his sockets as his cheerful demeanor turned into white hot rage. He lunched over the table at her, fortunate for her Stretch was quicker than his brother. Grabbing her wrist and teleporting out of the house. Blue hit the ground, making a roll over the floor to get back on his feet. “GET BACK HERE YOU DIRTY BROTHER FUCKER!!” He roared, ready to chase them down.

“ _Sans_.” You spoke low, slowly sliding your chair over the floor. He glared at you as you loomed over his white hot form. There was nothing left of the usual cheerful little skeleton.

“YOU.” He growled, pointing the knife at you. You growled back, you wouldn’t tolerate anyone pointing YOUR knife at you. You swiftly grabbed his wrist and flicked it. Blue yelped as the sharp stinging pain shot through his bones causing him to drop the knife. You picked it up and inspected it for damage before placing it away.

“Sit, Blue. We’re going to have a chat.” You commanded him. The little skeleton glared at you, tears in his sockets as he tended his hurt wrist. He kicked himself mentally for having underestimated you. He joined you on the couch. “Threaten me again and I will dust you.” You told him looking him dead in the socket. Blueberry had no doubt you would if he wasn’t careful. He nodded to show he understood. You sighed and gave him a stern look. “What you did was unacceptable.” You started. “Whatever Stretch and Blondie do together is none of your business; they’re adults for crying out loud.” You scolded him.

“But he is MY brother! That dirty slut is taking him away from me!” He yelled, an angry pout on his skull as he exaggerated by flailing his arms. You sighed, he was being thick-skulled…. You decided your next action. Quickly pouncing the small skeleton you bound his wrists above his head with your tie. Blue yelped in surprise but growled and struggled once he was pinned under your body. You push his bound wrists into the couch above his skull.

“Then I’ll just even the score~” You purred. “To cushion the blow~” You smirked, ripping the blue scarf from his neck and turning his skull to the side. Blue struggled and yelped feeling your teeth bite down on his sensitive cervical vertebrae, marking him. His anger quickly turning into fear as you littered his neck and shoulder with bite marks. He cried out again and again until he was a trembling mess under you. A few sobs escaped him before you let up from your attack. He looked at you with tears stinging his blue eye lights. It was the saddest expression you’d ever seen on the little skeleton. “Can you think straight again?” You asked, he nodded stifling a sob.

“…Was I not good enough?” He asked quietly. “Does Papy not love me?” He whimpered sadly. You gave him a soft gaze, bringing a hand to his cheekbone to caress it gently. A few tears slid down his skull.

“That’s not it, little Blueberry…” You whispered soothingly. “He loves you a lot…. Just not as a lover…” You told him wiping the tears from his sockets. “If he had he would have turned down the advances my friend made on him… Nor would he have flirted back…” You gave him a soft kiss on the forehead and softly rubbed his ribs. Blue sighed, slightly relaxing as you comfort him. Little shivers started to jolt down his back by the little kisses you placed in his neck, his magic starting to react to the stimuli. A soft gasp escaped him when you pressed a soft kiss against his teeth.

“H-human?” He questioned, taken aback by the sudden physical interaction. You hummed, hand sneaking under his shirt and stroking his spine. A shudder and soft moan your reward as his breathing started getting heavier. “W-what are you… hhnn… D-doing?” Blue asked squirming. Your eyes flicked up to his sockets.

“Making good on my promise.” You smirked, licking his vertebrae and stroking his spine. Blue’s sockets lidded, pleasure slowly over taking his senses. “I’m making you mine…” You whispered huskily against his skull. Blueberry’s magic jolted at the promise. A small moan escaping him, surprising himself. Maybe after trying so long to get in your good graces he started to actually care? He quivered feeling your hand palm his pelvis through his shorts. He gave you a heated look, teeth slightly parting in pants. The glow of the magic manifesting shining through. He made soft noises after being pulled into a kiss with you, tentatively kissing you back. Stars he was cute when he acted honestly. The magic in his shorts manifested itself as a pussy, surprising you. Not that you minded…

“Wh-wait… Aaahhh…. Hhnnn… W-wait!” Blue panted, trembling yet rolling his hips against your hand. “I-I…” He flustered, blue dusting his cheekbones as he shyly looked at you. “I ehm… I n-never done this with anyone else b-before…” He softly admitted. Oh stars he was still a pure snowflake in that area. Though you had no doubt he wasn’t exactly innocent either…

“I’ll be gentle…” You responded with a soft smile before claiming his mouth again. He softly whimpered a grateful noise. Gasping as you rubbed slow circles over his clothed folds. Blue gave up on trying to get out of the situation, your gentle ministrations too enjoyable for him to actually make the effort. Shifting his shirt up you kissed down his sternum, feeling him tremble under your body. You thumbed the top of his shorts, slowly pulling them off as you neared the end of his sternum. Blue squirmed under you, giving you a heated yet slightly worried expression. You tossed his shorts to the side, leaving his delicate flower exposed. Blue shivered at the sudden change of temperature. You looked at the untouched flower between his femurs, softly kissing its petals. Blue sighed pleased at the soft ministrations, worry pushed from his mind. Sure that he was comfortable now you prop up his trembling femurs over your shoulders gripping his hips and gently spreading his flower’s petals, eliciting a surprised gasp from him. You slowly ran the tip of your hot tongue between his wet folds, having him mewl and arch his back in the process.

“Aaahhh… Aaahh… Ahhhnnn… (Y-Y/n)…. Aahhh…. P-please…. Mmmooorreee~” He drawled in a moan. Pressing his pussy closer to your face. You gladly gave him what he wanted, pressing your tongue flat between his folds and tasting the whole of him. He let out a shuddery moan, pressing even closer against your tongue. “Aahh… Aahhh… y-yes… please… oohhh… aahnn…” He keened. You circled his clit, eliciting even more noises from the blue little skeleton. He was dripping, his juices spilling onto your tongue as you eagerly explored inside of him. “Aahh.. hhnnn… (y-y/n)! oohhh!… Aaahh!.. M-mmmoorrreee! P-please!” He begged, head swimming in lust, his bound hands gripping your hair and lightly tugging. His walls were twitching as you slowly rubbed your tongue against them, he was getting close. He whined in protest when you pulled away. The heat in his gut ready to burst. “N-no… aahnn! D-don’t… hhmmm… don’t stop!” He pleaded panting. You claimed his mouth, placing a finger to his entrance. He moaned, pressing against it to try and have you slip it in.

“Who do you belong to~?” You purred the question. Blue moaned, head swimming in pleasure so it took a while for the question to be processed. He whined, giving you a begging look.

“I-I…” He stammered. You slowly retracted your finger, leaving Blue feeling empty and heated. You looked away, slowly getting off of him.

“Well, I could just…” You started but were interrupted by a desperate Blue.

“YOURS!” He blurted out. “I-I’m y-yours! P-please…” He begged small tears in his sockets. You smiled, brushing your fingers against his folds. “Aaahhh!!” He mewled, pressing against them. You slowly pushed a finger in. “Hhhaaa….~!” Blue arched his back shuddering. His sockets closed shut letting the pleasure over take him. You thrust your digit in and out at a slow pace, curling it once in a while inside of Blue. He squirmed and mewled, drool dripping down his chin by now. You watched him jolt by you adding a second finger. “Aaahh… Aahh… (y/n) mmooore~ G-give me more~! P-please~” He whined canting his hips as you picked up the pace and watched him fuck himself on your fingers. Soft slick noises coming from his cunt mixed with his heated, lewd groans.

“That’s it… Good boy…” You cooed, watching him wither and writhe under you in pleasure. “Mewl for your master~” You purred sultry, adding a third finger, curling and spreading them once in a while inside him.

“Hhhaaa… hhhnnn… Aaahhh!… P-please~! Make me cum~! Aaahhnnn…. Oohh.. Ahn~ M-master!” Blueberry mewled, feeling the heat in his pelvis coil tighter and tighter. You growled pleased, speeding up and fucking him harder and deeper with your fingers. Blue keened, his breaths and mewls getting shorter and erratic as he neared his breaking point. “Aahh! Aahh! Aahh! I-I’m… I’m cumming! Aahh! Aahh! M-master!” He cried out as he came, your digits curling inside him and his juices dripping down your fingers. He trembled and made a small noise of protest as you pulled your hand away from his dripping cunt. He panted, looking up at you as you licked his essence from your fingers sensually.

“Hhhmmm~… Didn’t think you’d actually taste like blueberries~” You mused, Blue flustered and hid behind his hands. You chuckled, pulling them down and capturing him in another kiss. He could taste himself on you. If he wasn’t so spend he’d be turned on again. He closed his sockets as you got off him, scooping him up and setting him on your lap. You wrapped your arms around him, gently kissing his skull and neck. “Now then~ You won’t try to kill her again, will you? I’d hate to punish you if you tried…” You spoke, cupping his chin firmly.

“N-no, (y/n)…” He whispered, “I won’t…” He was dozing off, the sweet smell of jasmine filling his sense of smell. The anger in him quenched for the time being. He wouldn’t try to kill the other human but he wouldn’t accept her either. He curled into your chest. He had to admit though, this was nice… and with that Blue fell asleep in your arms.

**Author's Note:**

> Was originally up on wolf-n-bones.tumblr but due to the NSFW ban has been moved here  
> Hope you enjoyed it anyway~


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